it is your clutch telling you to replace it. lol
sounds like your clutch might be slipping and then catching
In case you still wondering, it's your clutch.You'd have to take the clutch off to actually inspect it. But it's your clutch. Many people on this forum have had the exact same scenario as you, including myself.
A bad turbo wouldn't behave like this and neither would the transmission. Just check out the million threads about bad clutches and you'll see yours is the same. Hope this helps